Ticlopidine or clopidogrel combined with aspirin decrease major cardiac events (Mace) after PTCA with stent implantation. It has not be proven yet that pretreatment by T or C was superior to conventional post-treatment, especially in unstable patients. The aim of the present study was to determine the influence of thienopyridine pretreatment on the risk of Mace (death, Q wave myocardial infarction, need for repeat PTCA or surgery, angina recurrence, stent thrombosis) during the hospitalization period in a population prospectively included in 2 multicentre registries of patients undergoing placement of a S670 or S7 stent (Medtronic) implanted in native coronary arteries (> or = 3.0 mm). Among the 2929 patients included into the registries, 1205 had unstable angina (41%). 50.2% of the patients were pretreated by T or C (T = 15.7%, C = 34.5%); 85.5% received aspirin before the procedure; definition of pretreatment was the administration of drug at least 6 hours before stent implantation. GPIIb-IIIa antagonists were administered in only 13.9% of patients. Mace were observed in 2% of the patients. Factors correlated with Mace by univariate and multivariate analyses were: age > 73 years (RR: 2.37; 95% CI: 1.05-5.36, P < 0.037), previous myocardial infarction (RR: 2.56; 95% CI: 1.08-6.11, P < 0.034), pretreatment by T or C (RR: 0.389; 95% CI: 0.16-0.95, P < 0.038). In patients who did not receive GPIIb-IIIa antagonists, age > 73, and pretreatment by T or C were the only independent predictors of Mace.